1. Field of the Invention
This invention relates to disks for use in disk drives and similar memory systems and in particular to an apertured disk and plug for use with the disk and a disk carrier in the manufacture of a disk which allows magnetic material to be coated simultaneously on the two surfaces of a disk without the passage of material from one side to the other side of the disk through the disk aperture during the coating process.
2. Prior Art
The manufacture of memory disks for use in disk drives and similar systems is well known in the art. In the manufacture of such circular disks, an aluminum or other suitable blank is coated on both sides with magnetic media, for example, a cobalt nickel-chromium alloy in which information will be stored. Typically the coating is done by sputtering. To implement the sputtering process it is well known to use vertical electrodes on each side of the disk and thus coat both surfaces of the disk simultaneously. During the coating process two things can happen. First, one electrode can be cross-contaminated by sputtered material from the other electrode passing by the disk. This causes particles to form on the target (i.e. the electrode) which later flake off and then land on the disk thereby changing the composition of the magnetic media and forming impurities on the surface of the disk. Second, the plasma from one electrode can interfere with the plasma from the other electrode thereby preventing uniform depositing of magnetic media on each disk surface. To prevent these two things from happening in the formation simultaneously of magnetic media on both sides of the disk, one electrode must be completely screened from the other electrode, including any central aperture of the disk which in actual use is mountable on the spindle of a disk drive.
In the coating of magnetic media on disk surfaces, a disk carrier is common used. The disk carrier must be designed so that it will not cause shadows on those portions of the disk surface on which magnetic media and other layers of material are being sputtered. Also, the carrier must be such that the disk can be easily loaded into the carrier by a human or a robot. In the prior art, the disk carriers have not been completely satisfactory in that the disk carrier typically has an opening between the top surface of the carrier and the disk which allows cross-contamination and plasma interference during the coating process and the disk central aperture is not properly sealed.